MisterMidlifeCrisis

Is there any way to direct air to the windshield and NOT have the a/c compressor come on? We run that way in all of our other vehicles from October through March and manually engage the compressor when it's needed to unfog the windows, but in the Corvette, the compressor runs practically continuously when any air is directed to the windshield, despite pressing the compressor-off button and having the HVAC display show that the compressor is off.

Is this something dealer programmable?

Bill Suttie

I assume you understand why the A/C compresor is on in defog/defrost mode. I am curious why you want to alter this. Does the dehumidified air dry your eyes? To program this you would have to get someone to activate the compressor descrete switch in defrost mode. A dealer wouldn't touch that. My guess is if a seperate switch were wired into the compresor clutch wire or the compressor clutch relay B+ (underhood fuse block) that might cause the system to throw a code.

MisterMidlifeCrisis

Yes, I understand why the compressor is on in defrost mode, but from October through March, the temps are between 35 and 55 degrees F., and both my wife and I wear contact lenses. With clean windows, it just doesn't fog unless we're sweating from working out or are wet from having gotten soaked in the rain. So, we have just always directed air towards the windshield these five or six months, but in every car we've had up until now, we could control the compressor as well and in the case of our 2010 Rav, it is a dealer programmable option whether or not to have the compressor explicitly obey the position of the A/C button.

Thanks for the info regarding the compressor. Sounds like it's not going to be easy.

Bill Suttie

I've been wrong before, talk to your dealer maybe they can help.

Gearhead Jim

So if you select the Defrost position and then push the Snowflake to turn off the compressor, the compressor continues to run?

Normally, I think the compressor only runs "when needed". If you can't turn it off, maybe selecting a slightly higher temperature would cause it to shut down at least for a while.

Grasping at straws...

MisterMidlifeCrisis

Yes, the compressor continues to run despite the indicator on the hvac display that it will not run. I don't think turning the temp up will have an effect on how often the compressor runs, because the ambient temp is way lower than the 60 degrees that is the lower limit for the display, so it must be using something else like humidity levels to determine how often to cycle the compressor.

I'll ask the dealer to see what they say. I have a feeling it's going to be an interesting conversation.

REVAK

I had the same issue years ago when gm dropped the selectable option. [ the dash controls used to have both defrost,[ no compressor ] , and defog, [with compressor ] . What I did back then was put a switch on the compressor clutch line, making it selectable. Haven't tried it yet on the C6, so I don't know if that would set a code.